The invention is directed to improved dual fuel feed manifold systems for high efficiency gas turbine engines which also have a drain manifold wherein all three manifolds are attached together to provide a structure with a resident frequency that resists vibration during operation of the gas turbine engine.
Vibrations within gas turbine engines poses a problem in that stress crack failures may result over a period of time. Vibration of certain components often results because the natural frequency of the component corresponds to the number of cycles (revolutions) of the engine over the operating range. Fuel manifold systems with a single annular fuel feed tube have been found to have many natural frequencies in the 1/rev engine operating range of conventional gas turbine engines. Fuel systems used for aircraft propulsion with dual fuel feed manifolds have been described in U.S. Pat. Nos. 4,903,478 and 4,312,185. The individual manifolds of a dual fuel feed system can be vulnerable to vibration from engine operation in the same manner as the manifold in single fuel feed systems. Applicants have now developed an integrated manifold system which utilizes dual fuel feed manifolds and has a high natural frequency above the 1/rev excitation range of the engine.